Wharram vs Mumby: the better and why

[BobFord]

My first boat was a Wharram 46 . Built 1970. Good travelling for a reasonable cost. Biggest mistake was fg sheathing on ply. Leave ply naked so it can dry out. This boat travelled 2x RTW ( not me ) and was last path crossed 5 y.o .

[catsketcher]

Gday Bob

I reckon you probably used polyester to do the glassing. It is a huge world away from using epoxy and glass. Personally I love having ply glassed with epoxy and a thin cloth. If it is not done then I get checking. With epoxy saturation, the last thing I want is for the play to breathe, it gets totally encapsulated in epoxy and just doesn't change, ever. Great stuff.

[BobFord]

G'day Catsketcher, Wise words re epoxy . Ply was epoxy impregnated but sheathing was poly!! In those days ,I guess $ was the motivation. Launched the damn thing without even a compass !! However , did cross Atlantic then bogged down , broke , in Gib. End of story for me and the Wharram.Met boat again in New Caledonia many ,many years later and was told the sad story re the sheathing .

[Sailorichiban]

Hello all.
I’ve been thinking of a catamaran for years now.
What hard chined boats are being discussed ?
I’m not a fan of building rounded shapes, although I have.
The inherent strength , of especially compound curves does have its appeal, but the the time in construction often seems hard to justify.
What are the the thoughts on encapsulated wooden construction regarding durability? How do you think it compares to using foam as substitute for wood.
Also comparing in terms of cost and weight/strength and time.
Any thoughts, especially backed up with real world experience, will be appreciated.
As some of my friends have said,” Thank you in advance for your cooperation! “

[Tupaia]

Originally Posted by Sailorichiban

Hello all.
I’ve been thinking of a catamaran for years now.
What hard chined boats are being discussed ?
I’m not a fan of building rounded shapes, although I have.
The inherent strength , of especially compound curves does have its appeal, but the the time in construction often seems hard to justify.
What are the the thoughts on encapsulated wooden construction regarding durability? How do you think it compares to using foam as substitute for wood.
Also comparing in terms of cost and weight/strength and time.
Any thoughts, especially backed up with real world experience, will be appreciated.
As some of my friends have said,” Thank you in advance for your cooperation! “

There are a good number of designers that have hard chine models, Richard Woods, Schionning, Bernd Kohler.


With the current price of decent plywood the cost difference and weight benefits of using foam are much better. No reason not to use flat panels and chines for ease of build.

[catsketcher]

Originally Posted by Sailorichiban

Hello all.
I’ve been thinking of a catamaran for years now.
What hard chined boats are being discussed ?
“

Like Tupaia says, plywood is getting more expensive. I like ply, but only until it needs framing, so I use it in my small folding cats because I can make it span up to about 500mm without stringers, but the hull bottom and decks are foam. My 38ft cat has ply decks (it was my first boat) ply bulkheads and interiors and strip plank hulls and a foam cabin. If I was to lose it and rebuild her, then I would do the decks in foam.

Foam is not always great - if under high load, the skins can delaminate and core can fail. So, although you can get lightweight skins, they may fail under stress and then it is much worse than ply, and well epoxied ply lasts forever, but not well epoxied ply can rot. Both materials can make great boats.

[Tupaia]

Originally Posted by catsketcher

Foam is not always great - if under high load, the skins can delaminate and core can fail. So, although you can get lightweight skins, they may fail under stress and then it is much worse than ply, and well epoxied ply lasts forever, but not well epoxied ply can rot. Both materials can make great boats.

Yes, there are different types of foam with different properties that need to be taken into account when deciding which to use.
As an example Divinycell is quite brittle when compared with say Airex.

[jalmberg]

This is so true, but you need experience to choose your ‘last boat’ and it doesn’t sound like the OP has that experience, yet. Building a boat is about the hardest way possible to get that experience. Much easier, faster, and cheaper is to crew on other people’s boats, but again, this is advice that few newbies have the nerve to take. Ah well. Good luck !

[sailingharry]

Originally Posted by Chotu

Until the end...

it is a miserable process all the way through until the end.

Once you have a boat that you could have never afforded or dreamed of owning, once you have made it through the gauntlet, it’s actually kind of nice.

I could not be happier with my boat. It’s my ideal boat. People talk about resale value sometimes when they build a boat. Why? Why would you ever sell the boat? if you pick the right one to build, you will only sell it once you are done boating. That’s why the OP really needs to focus and know what he wants before he builds it. There could be nothing worse than sacrificing all those years of your life for something you don’t really like

OP, you are new here, so you haven't heard Chotu's story for what seems like forever. And his posts in this thread haven't made it completely clear. He has mostly self-built a large performance catamaran he lives aboard. It's still not done, but it's getting close. You should search on his posts and threads, read them, and take them to heart--- the good and the bad. He knows of what he speaks.

[Factotum]

I purchased a Wharram Narai MKII from the builder on the south coast of England in 1989. He was selling the boat because he thought that it would only take 3 years to build. It took him 11 years to finish the boat, which was very finely constructed, and he and his wife were too old by then to go world sailing. The boat was essentially new when I bought it. The builder had rigged it as a sprit ketch, which made all of the sails smaller and much easier to handle. I never reefed a sail, but simply furled them one by one as the wind increased. With the flat deck, the boat was very safe for sail handling, etc.

The boat was covered with 6mm British Marine Plywood, had a solid Iroko keel, and hand carved spruce masts. Over the hull, he had saturated the ply with resorcinol glue and stuck canvas into the wet glue. The canvas was then impregnated with more resorcinol glue. It was called Cascover, and was inexpensive, light weight, and very effective. All of the iron was handmade and heavily galvanized. I never saw any rust.

My wife and I, along with our two children, sailed this boat 10,000 nm from England back to New Orleans. The average speed was 5 kts on the transatlantic. I would consider a Wharram catamaran again, but would look for a nicely built Wharram Pahi 42 Captain Cook. 22-foot beam, and only 2.5 foot draft. I boarded a Pahi 42 in the Canary Islands, and it seemed like a spacious yacht compared to our cramped hulls.

These Wharram cats do sail to windward, but only poorly. My cat had only a single outboard of 27 hp. They need two of at least 15 hp each to be able to turn the boat around in its own length. These boats are mostly very basic, simple sailboats, with few of the modern conveniences. No pressure water, kerosene lanterns for light in the hulls, kerosene primus stove, no diesel engine, solar panels for the autohelm, etc. We saw many people in harbors for lengthy times due to diesel malfunctions. If you cannot fix it yourself, and it is vital, it should not be on your boat.

With so many nice catamarans out there for sale, at low prices, life is really too short to build one yourself. Just buy one and go cruising!

[Huffa]

Originally Posted by Natureal1

Howdy!

I'm new here and in the process of picking either a Mumby 48 or a Wharram Tiki 46 to build. Big caveat is if I can even FIND the Mumby plans. Two days of searching have yet to turn any up.

Curious to hear those with experience weigh in on which would be the better blue water AND coastal (shallows) sailing. My own reading gives me the impression that a Mumby with some of the Wharrams features might be the safest, fastest, most durable, stable option.

Thoughts and musings?

Thanks!
PS-- was trying to have this posted in the "Wharram" thread I had found.

You probably will get the mumby plans through the boat designer guy.
I know he's based in queensland, australia. One of my friends bought his plans.

regards,
Huffa.

[Rjstutch]

Tim Mumby has gone cruising again. He was building his 48's in aluminium in the Philippines, but said last time he was interviewed he was going cruising when he finished these last 3 boats and he would be uncontactable.
I am sure he would get someone to sell his plans while he is away for a few years.

[JustMurph]

There is some great advice in this thread. Any questions on the Mumby, please ask (I'm an owner). If you're serious about buying the plans, let me know and I'll give you Tim's contact.

[double u]

"Wharram vs Mumby: the better and why"

asking this question shows, that the first thing for you to do, before you take ANY action (like buying plans,...), is to educate yourself about boats in general, catamarans in particular & boatbuilding!
(& concerning boatbuilding: any building time or material-costs you read about: double them!)

[Tupaia]

Originally Posted by double u

"Wharram vs Mumby: the better and why"

asking this question shows, that the first thing for you to do, before you take ANY action (like buying plans,...), is to educate yourself about boats in general, catamarans in particular & boatbuilding!
(& concerning boatbuilding: any building time or material-costs you read about: double them!)

There is an excellent book by Derek Harvey - "Multihulls for Cruising and Racing" that I would recommend to anyone in this position. Although it doesn't cover more up to date models it describes in detail fundamental differences between styles without bias.